From Trash to Treasure

Design of a gripper for automated sorting of mixed aluminium scrap to create added value

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Reukema is the biggest non-ferrous trader in the Netherlands. They want to investigate the possibility of sorting aluminium in a robotic system. Aluminium is one of the most used materials worldwide. Demands for aluminium are ever increasing. Recycling scrap is needed to keep up with the demand. An important step in the recycling process is the separation into different alloys, as sorting aluminium creates added value. Currently, the only way to sort the scrap is to have it done manually in low-wage countries such as China, Pakistan or India. This thesis describes the analysis of the problems which may occur implementing such a system. Three idea directions were generated based on the analysis executed. It was found that using a robotic arm with a robotic gripper would unwantedly increase the complexity of the sorting system. Simply pushing the scrap off a conveyor belt was found to be the best design. Based on this finding three different concepts were created, of which one, the concept in which material is fed into the system in a line, was selected. A pusher, perpendicular to the conveyor belt, pushes the material off the belt. Material is classified using a camera and a line scanner. The scrap is stored in a bunker under the sorting installation. In the last phase of this project the gripper was detailed. It was important to maximize the quality of sorting. Besides this, the reliability of the complete system needed to be maximized, while the cost per tonne should be minimized. The final design is a gripper which gives the pieces of scrap a parabolic trajectory before they land in the bunker for storing. The gripper is constructed out of steel and is 250 by 125 [mm]. A rib of 100 [mm] was added to lift pieces of scrap off the conveyor belt and decrease friction.